Calendering processes are well-known and are disclosed, for example, in U.S. Pat. Nos. 3,159,516; 3,457,139; 3,505,143; 3,589,975; 3,623,933; 3,767,510; 3,930,922; and 3,976,528.
U.S. Pat. Nos. 3,483,664, 3,575,779 and 3,753,938 all discloses laminates of chlorinated polyethylene. In these prior art patents a laminate of three layers had to be formed by two passes through a calender or by heat-pressing.
Previously used pipe-wrapping materials have not provided adequate impermeability and weatherability. A metal pipe-wrapping material is not adequately resistant to the weather and can have the disadvantage of being a conductor of electricity. Thermoplastic material alone is not sufficiently resistant to vapor permeation. Additionally, the sealing of pipe-wrapping materials, particularly for cryogenic applications, often does not produce good vapor-tight and water-tight seals.